The present invention relates to a tube cutting apparatus for use in a continuous tube manufacturing plant, wherein a coiled strip is made into a continuous tube. In such plants, tubing is cut by a traveling cutting apparatus into desired lengths.
Such apparatuses are known, for example, from U.S. Pat. Nos. 4,149,438, and 4,637,287, the latter of which is assigned to the assignee of the present invention. In such machines, and other generally similar machines, a rotating press assembly is used to actuate a cutting assembly which includes a cutting blade. A crankshaft associated with the press assembly generates a cranking force which is distributed over a ram along which the cutting assembly slides. In general, forceful rotation of the crankshaft is in a single, or forward, direction. By limiting the forceful rotation of the crankshaft to only one direction, the angular extent during which the crankshaft can be accelerated to the proper cutting velocity is restricted. As a result, the rate of acceleration of the crankshaft is substantially larger than it would be if the crankshaft were forcefully rotatable in both a forward and reverse direction. By allowing forceful rotation of the crankshaft in forward and reverse directions, the rate of acceleration of the crankshaft can be reduced. As a result, the size of the motor used to accelerate the crankshaft can be reduced. Alternatively, if the size and power rating of the motor is maintained at the same level, by providing both forward and reverse rotation, the life of the motors and associated driving and stopping equipment can be prolonged.
It is therefore an object of the present invention to provide a tube cutting apparatus with improved efficiency.
It is another object of the present invention to provide a tube cutting apparatus which employs smaller, less expensive motors.
Yet another object of the present invention is to provide a tube cutting apparatus which has improved service life.
Still another object of the present invention is to provide a more efficient and economical method of cutting tubing.
These and other objects of the invention are achieved with a tube cutting apparatus in which the motor which drives a rotating crankshaft can be forcefully rotated in both the forward and reverse directions. The invention, which is particularly useful in a tube manufacturing plant, continuously generates tubing in a linear direction at a substantially constant speed. An elongated ram is used to actuate a cutting assembly. The cutting assembly is accelerated to a velocity which matches that of the tubing being produced. The ram is driven by a crankshaft which rotationally accelerates the ram, causing movement of a cutting blade through the tubing. The motor which drives the crankshaft is capable of forceful acceleration of the crankshaft in both forward and reverse directions. As a result, the acceleration and deceleration rates of the crankshaft can be minimized. By reducing the acceleration and deceleration rates, smaller capacity motors and simpler controls can be utilized.